Modern data communication networks play a critical role in everyday interpersonal interactions. In particular, the global nature of data communication networks allows instantaneous communication with anyone, anywhere in the world. Given these benefits, it is not surprising that some experts estimate that traffic on the world's networks will continue to double every two years.
As these networks have expanded, customers of data communications service providers have increased their expectations. For example, many corporations have a number of geographically-scattered local networks, yet desire seamless communication between each of the networks. As a similar example, many businesses desire to link voice traffic between individual sites.
Formerly, guaranteeing a high quality of service for such arrangements required the customer to lease a separate line for use in transporting data belonging to Layer 2 of the Open Systems Interconnection (OSI) model. Though reliable and effective in meeting the customers' needs, the use of such leased lines proved to be an expensive solution.
Given the worldwide reach of Internet Protocol (IP) networks, service providers saw an opportunity to capitalize on the existing IP infrastructure. In particular, to address the demand for transparent transport of data from one site to another, service providers developed so-called Virtual Leased Line (VLL) services. VLL services are also known as Virtual Private Wire Services (VPWS). Using VLL services, a service provider may seamlessly transfer a customer's Layer 2 traffic (e.g., Ethernet, Asynchronous Transfer Mode (ATM), and Frame Relay) over an IP network.
In a typical VLL arrangement, a customer desires to transmit data from a local customer edge device to a remotely-located, far-end customer edge device. To facilitate this arrangement, the service provider implements two provider edge nodes, one on each side of an IP network between the customer edge devices. To exchange data between the customer edge devices, the customer need only connect each customer edge device to a corresponding provider edge node. The provider edge nodes, in turn, encapsulate the Layer 2 data, forward the Layer 3 data to one another over an IP pseudowire, then transmit the Layer 2 data to the Layer 2 address of the destination customer edge device.
It should be apparent from this description that, in order to properly forward data to the destination customer edge device, the connected provider edge node must be aware of the IP address and Media Access Control (MAC) address of the customer edge device. To avoid the time-consuming process of manually specifying each address, many service providers implement an automatic discovery process in which each customer edge device informs the provider edge node of its IP address and MAC address. In some situations, such as failure of the provider edge link, however, the provider edge node will remove or otherwise lose the IP to MAC address mappings. Furthermore, the customer edge device may be unaware of the problem when it is connected over a Layer 2 switch and, in such a circumstance, will not send an additional message notifying the provider edge node of its addresses.
In view of the foregoing, it would be desirable to implement a provider edge node that allows for automatic discovery of IP and MAC addresses, while providing a mechanism to maintain updated MAC address to IP address associations of connected customer edge devices, even in the event of failure of the provider edge node. Other desirable aspects will be apparent to those of skill in the art upon reading and understanding the present specification.